// Adapted from the archive library (https://pub.dev/packages/archive)
// https://github.com/brendan-duncan/archive/blob/21c864efe0df2b7fd962b59ff0a714c96732bf7d/lib/src/util/crc32.dart
//
// The MIT License
//
// Copyright (c) 2013-2021 Brendan Duncan.
// All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

/// Util class to compute the CRC-32 checksum of a given array.
class Crc32Utils {
  /// Get the CRC-32 checksum of the given array. You can append bytes to an
  /// already computed crc by specifying the previous [crc] value.
  static int getCrc32(List<int> array, [int crc = 0]) {
    var len = array.length;
    crc = crc ^ 0xffffffff;
    var ip = 0;
    while (len >= 8) {
      crc = _crc32Table[(crc ^ array[ip++]) & 0xff] ^ (crc >> 8);
      crc = _crc32Table[(crc ^ array[ip++]) & 0xff] ^ (crc >> 8);
      crc = _crc32Table[(crc ^ array[ip++]) & 0xff] ^ (crc >> 8);
      crc = _crc32Table[(crc ^ array[ip++]) & 0xff] ^ (crc >> 8);
      crc = _crc32Table[(crc ^ array[ip++]) & 0xff] ^ (crc >> 8);
      crc = _crc32Table[(crc ^ array[ip++]) & 0xff] ^ (crc >> 8);
      crc = _crc32Table[(crc ^ array[ip++]) & 0xff] ^ (crc >> 8);
      crc = _crc32Table[(crc ^ array[ip++]) & 0xff] ^ (crc >> 8);
      len -= 8;
    }
    if (len > 0) {
      do {
        crc = _crc32Table[(crc ^ array[ip++]) & 0xff] ^ (crc >> 8);
      } while (--len > 0);
    }
    return crc ^ 0xffffffff;
  }
}

// Precomputed CRC table for faster calculations.
const List<int> _crc32Table = [
  0,
  1996959894,
  3993919788,
  2567524794,
  124634137,
  1886057615,
  3915621685,
  2657392035,
  249268274,
  2044508324,
  3772115230,
  2547177864,
  162941995,
  2125561021,
  3887607047,
  2428444049,
  498536548,
  1789927666,
  4089016648,
  2227061214,
  450548861,
  1843258603,
  4107580753,
  2211677639,
  325883990,
  1684777152,
  4251122042,
  2321926636,
  335633487,
  1661365465,
  4195302755,
  2366115317,
  997073096,
  1281953886,
  3579855332,
  2724688242,
  1006888145,
  1258607687,
  3524101629,
  2768942443,
  901097722,
  1119000684,
  3686517206,
  2898065728,
  853044451,
  1172266101,
  3705015759,
  2882616665,
  651767980,
  1373503546,
  3369554304,
  3218104598,
  565507253,
  1454621731,
  3485111705,
  3099436303,
  671266974,
  1594198024,
  3322730930,
  2970347812,
  795835527,
  1483230225,
  3244367275,
  3060149565,
  1994146192,
  31158534,
  2563907772,
  4023717930,
  1907459465,
  112637215,
  2680153253,
  3904427059,
  2013776290,
  251722036,
  2517215374,
  3775830040,
  2137656763,
  141376813,
  2439277719,
  3865271297,
  1802195444,
  476864866,
  2238001368,
  4066508878,
  1812370925,
  453092731,
  2181625025,
  4111451223,
  1706088902,
  314042704,
  2344532202,
  4240017532,
  1658658271,
  366619977,
  2362670323,
  4224994405,
  1303535960,
  984961486,
  2747007092,
  3569037538,
  1256170817,
  1037604311,
  2765210733,
  3554079995,
  1131014506,
  879679996,
  2909243462,
  3663771856,
  1141124467,
  855842277,
  2852801631,
  3708648649,
  1342533948,
  654459306,
  3188396048,
  3373015174,
  1466479909,
  544179635,
  3110523913,
  3462522015,
  1591671054,
  702138776,
  2966460450,
  3352799412,
  1504918807,
  783551873,
  3082640443,
  3233442989,
  3988292384,
  2596254646,
  62317068,
  1957810842,
  3939845945,
  2647816111,
  81470997,
  1943803523,
  3814918930,
  2489596804,
  225274430,
  2053790376,
  3826175755,
  2466906013,
  167816743,
  2097651377,
  4027552580,
  2265490386,
  503444072,
  1762050814,
  4150417245,
  2154129355,
  426522225,
  1852507879,
  4275313526,
  2312317920,
  282753626,
  1742555852,
  4189708143,
  2394877945,
  397917763,
  1622183637,
  3604390888,
  2714866558,
  953729732,
  1340076626,
  3518719985,
  2797360999,
  1068828381,
  1219638859,
  3624741850,
  2936675148,
  906185462,
  1090812512,
  3747672003,
  2825379669,
  829329135,
  1181335161,
  3412177804,
  3160834842,
  628085408,
  1382605366,
  3423369109,
  3138078467,
  570562233,
  1426400815,
  3317316542,
  2998733608,
  733239954,
  1555261956,
  3268935591,
  3050360625,
  752459403,
  1541320221,
  2607071920,
  3965973030,
  1969922972,
  40735498,
  2617837225,
  3943577151,
  1913087877,
  83908371,
  2512341634,
  3803740692,
  2075208622,
  213261112,
  2463272603,
  3855990285,
  2094854071,
  198958881,
  2262029012,
  4057260610,
  1759359992,
  534414190,
  2176718541,
  4139329115,
  1873836001,
  414664567,
  2282248934,
  4279200368,
  1711684554,
  285281116,
  2405801727,
  4167216745,
  1634467795,
  376229701,
  2685067896,
  3608007406,
  1308918612,
  956543938,
  2808555105,
  3495958263,
  1231636301,
  1047427035,
  2932959818,
  3654703836,
  1088359270,
  936918000,
  2847714899,
  3736837829,
  1202900863,
  817233897,
  3183342108,
  3401237130,
  1404277552,
  615818150,
  3134207493,
  3453421203,
  1423857449,
  601450431,
  3009837614,
  3294710456,
  1567103746,
  711928724,
  3020668471,
  3272380065,
  1510334235,
  755167117
];
